1. Field of the Invention
The present invention relates to apparatus for trimming the molding flash that exists at the bottle neck and top, at the bottle base, and at the bottle handle from blow molded plastics bottles having an integral handle. More particularly, the present invention relates to a bottle trimming apparatus in which the flash is trimmed from a blow molded plastics bottle after the bottle has left the blow mold, and in which the flash removal is effected by gripping the bottle at the bottle handle, pushing the handle opening flash from the handle opening, and then pulling the neck and base flash material from the bottle.
2. Description of the Related Art
Although plastics bottles can be produced by injection molding, they are most often produced, especially in the larger bottle sizes, by a blow molding operation in which an extruded tubular parison of heated plastics material is placed between the separated parts of a two-part mold that defines a mold cavity to conform with the desired outer shape of the bottle. The mold parts are then brought together so that the parison is enclosed between the mold parts, which clamp the bottom of the parison closed and in which the top of the parison extends through the bottle neck opening defined by the mold parts. Pressurized air is introduced into the parison through the top opening to cause the tubular parison wall within the mold cavity to expand outwardly and to contact the surfaces of the blow mold, to thereby form a bottle having a shape defined by the mold cavity.
In the extrusion blow molding process the tubular parison is open at both ends and has a length that is greater than the axial height of the bottle to be blown. When the mold is enclosed around the parison, so both the upper and the lower ends of the parison extend outwardly from the neck and the base of the bottle mold, and thus an excess of plastic material remains attached to the base and the bottle neck after the blowing operation has been completed and the bottle is removed from the mold. The trimming of such excess material, referred to as "flash," can be removed in various ways, including twisting, shearing, pulling, and tearing.
The prior art has disclosed apparatus that serves to twist off the flash from a molded bottle, either while the bottle is still in the blow mold, or after the bottle has been removed from the mold for subsequent processing. Examples of such disclosures include U.S. Pat. No. 2,994,103, which issued Aug. 1, 1961, to Wilbur A. Schaich; and U.S. Pat. No. 3,994,651, which issued Nov. 30, 1976, to Taketoshi Kamibayashi.
Apparatus for shearing the flash from adjacent the neck of a blow molded bottle and also adjacent the base is disclosed in U.S. Pat. No. 3,795,162, which issued Mar. 5, 1974, to Ben E. Jaeger. The trimming devices involve progressive shearing of the flashing material along the bottle contour to provide a flash-free finished bottle.
Several prior art disclosures of trimming apparatus teach the removal of blow molded bottle flash by pulling the flash from the bottle. Examples of devices that operate in that manner are disclosed in U.S. Pat. No. 3,172,152, which issued Mar. 9, 1965, to A. R. Uhlig; U.S. Pat. No. 4,361,531, which issued Nov. 30, 1982, to Michael Black; and U.S. Pat. No. 3,901,637, which issued Aug. 26, 1975, to Noel B. Eggert.
An approach to the removal of the flash that remains in the opening defined by an integral bottle carrying handle is disclosed in U.S. Pat. No. 3,892,513, which issued Jul. 1, 1975, to Gottfried Mehnert et al. The handle flash or slug is removed while the bottle remains in the blow mold.
The removal of flash by a combination of shearing and pulling is disclosed in U.S. Pat. No. 3,464,084, which issued Sep. 2, 1969, to Robert D. Thompson, in which shear plates are disclosed for severing the flash at the top or neck portion of the bottle, and the bottom flash is removed by holding the flash and pushing the bottle away from the flash holder.
Finally, in U.S. Pat. No. 4,944,667, which issued Jul. 31, 1990, to Thomas F. Greene, apparatus is disclosed involving clamps having open areas to simultaneously grip only the neck flash portion of a series of aligned plastics bottles, the clamps adapted to pivot laterally while the bottles are held to tear the flash from the neck portions of the bottles.
Although a number of different approaches to the problem of removal of flash from blown plastics bottles have bee disclosed, each of the disclosed approaches involves complicated and costly apparatus, and if not properly operated the disclosed apparatus can damage a bottle and render it unacceptable.
It is an object of the present invention to provide bottle flash trimming apparatus that is simpler and more reliable than the prior art devices.
It is another object of the present invention to provide bottle trimming apparatus for trimming the flash from a bottle after the bottle has been removed from the blow mold.
A still further object of the present invention is to provide bottle trimming apparatus that completely removes the flash at the neck, base, and handle opening, and to dispose of it in a controlled fashion.
A still further object of the present invention is to provide bottle trimming apparatus that removes the neck portion flash without distorting the bottle neck or the closure-receiving threads at the neck.
It is still a further object of the present invention to provide bottle trimming apparatus that does not require critical bottle alignment, and that consequently minimizes damaged bottles resulting from improper positioning of the bottle relative to a punch or die structure.
It is still a further object of the present invention to provide bottle trimming apparatus that is able to accommodate bottles having different sizes and styles without the need for complicated additional equipment to adapt the apparatus to accommodate such different sizes and styles.
Additional objects and advantages to be derived from use of the apparatus and method of the present invention will become apparent from the accompanying description and drawings.